The development and status of Bt rice in China

Multiple lines of transgenic rice expressing insecticidal genes from the bacterium Bacillus thuringiensis (Bt) have been developed in China, posing the prospect of increases in production with decreased application of pesticides. We explore the issues facing adoption of Bt rice for commercial production in China. A body of safety assessment work on Bt rice has shown that Bt rice poses a negligible risk to the environment and that Bt rice products are as safe as non‐Bt control rice products as food. China has a relatively well‐developed regulatory system for risk assessment and management of genetically modified (GM) plants; however, decision‐making regarding approval of commercial production has become politicized, and two Bt rice lines that otherwise were ready have not been allowed to enter the Chinese agricultural system. We predict that Chinese farmers would value the prospect of increased yield with decreased use of pesticide and would readily adopt production of Bt rice. That Bt rice lines may not be commercialized in the near future we attribute to social pressures, largely due to the low level of understanding and acceptance of GM crops by Chinese consumers. Hence, enhancing communication of GM crop science‐related issues to the public is an important, unmet need. While the dynamics of each issue are particular to China, they typify those in many countries where adoption of GM crops has been not been rapid; hence, the assessment of these dynamics might inform resolution of these issues in other countries.     

Development of a model system to assess the impact of genetically modified corn and aubergine plants on arbuscular mycorrhizal fungi

We developed an experimental model system to monitor the impact of generically modified (GM) plants on arbuscular mycorrhizal (AM) fungi, a group of non-target soil microorganisms, fundamental for soil fertility and plant nutrition. The system allowed us to study the effects of root exudates of both commercial Bt corn and aubergine plants expressing Dm-AMP1 defensin on different stages of the life cycle of the AM fungal species G. mosseae. Root exudates of Bt 176 corn significantly reduced pre-symbiotic hyphal growth, compared to Bt 11 and non-transgenic plants. No differences were found in mycelial growth in the presence of Dm-AMP1 and control plant root exudates. Differential hyphal morphogenesis occurred irrespective of the plant line, suggesting that both exuded Bt toxin and defensin do not interfere with fungal host recognition mechanisms. Bt 176 affected the regular development of appressoria, 36% of which failed to produce viable infection pegs. Our experimental model system represents an easy assay for testing the impact of GM plants on non-target soil-borne AM fungi.     

Normal expression of insect-resistant transgene in progeny of common wild rice crossed with genetically modified rice: its implication in ecological biosafety assessment

Transgene outflow from genetically modified (GM) rice to its wild relatives may cause undesirable ecological consequences. Understanding the level of transgene expression in wild rice following gene flow is important for assessing such consequences, providing that transgene escape from GM rice cannot be prevented. To determine the expression of a transgene in common wild rice (Oryza rufipogon), we analyzed the content of Cry1Ac protein in three GM rice lines containing a Bt transgene, their F₁ hybrids with common wild rice and F₂ progeny at different growth stages, using the sandwich enzyme-linked immunosorbent assay. The average content of Cry1Ac protein in leaf samples of the wild rice lines ranged between 0.016 and 0.069% during the entire growth period, whereas that in stems varied between 0.12 and 0.39%. A great variation in Cry1Ac protein content was detected among individuals of F₁ hybrids and F₂ progeny, with some wild individuals showing higher level of Bt toxin than the cultivated GM rice. The results suggest that the Bt transgene can express normally in the interspecific hybrids between insect-resistant GM rice and common wild rice, and may have similar effects on the target insects as in GM rice.     

Effects of a diet containing genetically modified rice expressing the Cry1Ab/1Ac protein (Bacillus thuringiensis toxin) on broiler chickens

The aim of this study was to evaluate the effect of feeding Bacillus thuringiensis (Bt) rice expressing the Cry1Ab/1Ac protein on broiler chicken. The genetically modified (GM) Bt rice was compared with the corresponding non-GM rice regarding performance of feeding groups, their health status, relative organ weights, biochemical serum parameters and occurrence of Cry1Ab/1Ac gene fragments. One hundred and eighty day-old Arbor Acres female broilers with the same health condition were randomly allocated to the two treatments (6 replicate cages with 15 broilers in each cage per treatment). They received diets containing GM rice (GM group) or its parental non-GM rice (non-GM group) at 52–57% of the air-dried diet for 42 days. The results show that the transgenic rice had a similar nutrient composition as the non-GM rice and had no adverse effects on chicken growth, biochemical serum parameters and necropsy during the 42-day feeding period. In birds fed the GM rice, no transgenic gene fragments were detected in the samples of blood, liver, kidneys, spleen, jejunum, ileum, duodenum and muscle tissue. In conclusion, the results suggest that Bt rice expressing Cry1Ab/1Ac protein has no adverse effects on broiler chicken. Therefore, it can be considered as safe and used as feed source for broiler chicken.     

Effects of genetically modified maize events expressing Cry34Ab1, Cry35Ab1, Cry1F,and CP4 EPSPS proteins on arthropod complex food webs

Four genetically modified (GM) maize (Zea mays L.) hybrids (coleopteran resistant, coleopteran and lepidopteran resistant, lepidopteran resistant and herbicide tolerant, coleopteran and herbicide tolerant) and its non‐GM control maize stands were tested to compare the functional diversity of arthropods and to determine whether genetic modifications alter the structure of arthropods food webs. A total number of 399,239 arthropod individuals were used for analyses. The trophic groups’ number and the links between them indicated that neither the higher magnitude of Bt toxins (included resistance against insect, and against both insects and glyphosate) nor the extra glyphosate treatment changed the structure of food webs. However, differences in the average trophic links/trophic groups were detected between GM and non‐GM food webs for herbivore groups and plants. Also, differences in characteristic path lengths between GM and non‐GM food webs for herbivores were observed. Food webs parameterized based on 2‐year in‐field assessments, and their properties can be considered a useful and simple tool to evaluate the effects of Bt toxins on non‐target organisms.     

An approach for post‐market monitoring of potential environmental effects of Bt‐maize expressing Cry1Ab on natural enemies

Post‐market monitoring (PMM) consistent with Swiss and European Union legislation should ensure the detection and prevention of adverse effects on the environment possibly deriving from commercial cultivation of genetically modified (GM) crops. Insect‐resistant GM crops (such as Bt‐maize) raise particular questions regarding disturbances of biological control functions provided by beneficial insects such as predators and parasitoids (so‐called natural enemies). Consensus among regulators, scientists and the agricultural biotech industry on appropriate PMM plans allowing the detection and possibly prevention of such adverse effects is still lacking. The aims of this study were to identify the necessity for PMM of Bt‐maize expressing Cry1Ab on natural enemies and to develop an appropriate PMM plan. The approach chosen consisted in determining what type of monitoring is most appropriate to address potential effects of Bt‐maize on natural enemies during commercial cultivation. This included identifying whether there remain substantial scientific uncertainties that would support case‐specific monitoring. Existing pre‐market risk assessment data indicate that Bt‐maize (Cry1Ab) comprises a negligible risk for disturbances in biological control functions of natural enemies. As a consequence, a faunistic monitoring of specific groups of natural enemies is not considered an appropriate approach to detect failures in biological control functions. Alternatively, an approach is proposed that consists in indirectly analysing biological control functions by surveying outbreaks of maize herbivores. Unusual herbivore outbreaks could indicate failures in biological control functions of natural enemies. Data could be collected via questionnaires addressed to farmers growing Bt‐maize. Significant correlations between unusual occurrences of specific maize herbivores and the cultivation of Bt‐maize would subsequently need specific studies to determine possible causalities in more detail. The here proposed approach has the advantage of covering different natural enemy groups. It represents a cost‐effective strategy to obtain scientifically sound data as a basis for regulatory decision‐making.     

Risk assessment of Bacillus thuringiensis in wild Brassica rapa: A field simulation of introgressed transgenes

Abstract

Brassica crops are able to hybridize with closely related wild and weedy species such as Brassica rapa and therefore these species could become recipients of transgenes from GM brassica crops, such as oilseed rape. Transgenes which protect against herbivory, such as a gene conferring the production of a Bt toxin, could increase the recipient's fitness and therefore enhance its competitiveness. We used microbial Bt and several other pesticides to exclude several guilds of herbivores and thus simulate the effect of transgene introgression on the performance of wild B. rapa. There were only minor negative effects of excluding insect herbivores on the performance of B. rapa and it appears that vertebrate herbivory has a more significant effect. The advantages and disadvantages of simulating the risks associated with GM plants are discussed. If we apply this simulation to GM risk assessment and make inferences from these findings, the implications of this for gene flow from insect-resistant transgenic plants are that it will be of little significance should it occur.     

Host-plant mediated effects of transgenic maize on the insect parasitoid Campoletis sonorensis (Hymenoptera: Ichneumonidae)

Determining the impact of genetically modified (GM) crops on beneficial organisms is an important aspect of the environmental risk assessment of GM crops. In the present study, the impact of Bt maize expressing Cry1Ab on the development and behaviour of the parasitoid Campoletis sonorensis was compared to individuals reared on hosts fed conventionally bred plants partially resistant to the European corn borer (Ostrinia nubilalis Hübner) and on susceptible maize hybrids. Adult parasitoids reared on Bt maize-fed Spodoptera frugiperda larvae were significantly smaller (15–30%) than those reared in hosts fed either of the conventional maize hybrids. The magnitude of this effect was dependent on the size of the host at oviposition and its subsequent growth rate. The development time of C. sonorensis was not affected by the maize treatment. In choice tests, female parasitoids displayed no preference for hosts fed a specific maize hybrid. No Cry1Ab was detected within adult parasitoids.     

Molecular characterization of lepidopteran pest-resistant transgenic rice events expressing synthetic Cry1Ac

The insecticidal toxin gene of Bacillus thuringiensis (Bt) is one of the most commonly used in the development of genetically modified (GM) crops. In this research, we analyzed Bt rice showing lepidopteran pest-resistance. The Bt gene is a synthetic Cry1Ac composed of optimal codons for plants, and the Bt protein is targeted to the chloroplast by a transit peptide. Three Cry1Ac rice events (C103-3, C127-1, and C7-1) were analyzed for molecular characterization. C103-3 contains two copies of T-DNA where the left border (LB) region is truncated. Both C7-1 and C127-1 have a single copy of T-DNA, but a part of the vector backbone DNA is inserted into the genome of C127-1; thus, only C7-1 had intact T-DNA. Progenies of C7-1 crossed with the original cultivar, Nakdong, and double-haploid lines from anther culture of lines crossed with the elite cultivar, Dongjin, were analyzed for T-DNA flanking genomic DNA and genotyping. Results showed that an intact T-DNA region without the vector backbone was inserted into the genome and was stably inherited through generations. The C7-1 homozygous event could be used as breeding material to develop GM rice with pest resistance.     

Assessment of transgene flow in tomato and potential effects of genetically modified tomato expressing Cry3Bb1 toxins on bumblebee feeding behaviour

One of the concerns surrounding the commercial release of genetically modified (GM) crops is the escape of transgenes into agricultural or semi‐natural habitats through vertical gene flow, as this may cause environmental or economic problems. There is also the concern that GM crops may affect pollinators and the pollination services they provide. Despite the growing commercial interest of GM tomato (Solanum lycopersicum), gene flow has been assessed only sparsely in tomato. To evaluate the likelihood of gene flow from GM tomato plants to sexually compatible plants, and to assess whether bumblebee activity is affected by GM tomato, three experiments were conducted under greenhouse conditions, using a Bt‐tomato expressing the insecticidal Cry3Bb1 protein as model system: (a) artificial crosses between a GM tomato line, two wild tomato relatives (Solanum hirsutum and Solanum nigrum) and a non‐GM tomato variety; (b) bumblebee‐mediated crosses between GM and non‐GM tomato plants and (c) visual observations of bumblebees' feeding behaviour. No hybrids were obtained between the GM tomato line and S. hirsutum and S. nigrum. In an experimental design where non‐GM receptor plants outnumbered GM plants by approximately 3:1, the bumblebee‐mediated cross‐fertilisation rate between GM and non‐GM tomato plants was measured at 4.3 ± 5.47%. No significant differences in feeding behaviour of bumblebees foraging on GM and non‐GM tomato plants were observed. Therefore, we conclude that: (a) the probability of transgene introgression between the GM tomato line used in this study and its wild relatives S. hirsutum and S. nigrum is negligible; (b) bumblebee activity can mediate cross‐fertilisation between GM and non‐GM tomato and (3) the Cry3Bb1‐expressing tomato line tested does not adversely affect the feeding behaviour of bumblebees.     

Bt rice could provide ecological resistance against nontarget planthoppers

Genetically engineered (GE) rice lines expressing Lepidoptera‐active insecticidal cry genes from the bacterium Bacillus thuringiensis (Bt) have been developed in China. Field surveys indicated that Bt rice harbours fewer rice planthoppers than non‐Bt rice although planthoppers are not sensitive to the produced Bt Cry proteins. The mechanisms underlying this phenomenon remain unknown. Here, we show that the low numbers of planthoppers on Bt rice are associated with reduced caterpillar damage. In laboratory and field‐cage experiments, the rice planthopper Nilapavata lugens had no feeding preference for undamaged Bt or non‐Bt plants but exhibited a strong preference for caterpillar‐damaged plants whether Bt or non‐Bt. Under open‐field conditions, rice planthoppers were more abundant on caterpillar‐damaged non‐Bt rice than on neighbouring healthy Bt rice. GC–MS analyses showed that caterpillar damage induced the release of rice plant volatiles known to be attractive to planthoppers, and metabolome analyses revealed increased amino acid contents and reduced sterol contents known to benefit planthopper development. That Lepidoptera‐resistant Bt rice is less attractive to this important nontarget pest in the field is therefore a first example of ecological resistance of Bt plants to nontarget pests. Our findings suggest that non‐Bt rice refuges established for delaying the development of Bt resistance may also act as a trap crop for N. lugens and possibly other planthoppers.     

Effects of seed mixture sowing with transgenic Bt rice and its parental line on the population dynamics of target stemborers and leafrollers,and non‐target planthoppers

The widespread planting of insect‐resistant crops has caused a dramatic shift in agricultural landscapes, thus raising concerns about the potential impacts on both target and non‐target pests. In this study, we examined the potential effects of intra‐specific seed mixture sowing with transgenic Bt rice (Bt) and its parental non‐transgenic line (Nt) (100% Bt rice [Bt₁₀₀], 5% Nt+95% Bt [Nt₀₅Bt₉₅], 10% Nt+90% Bt [Nt₁₀Bt₉₀], 20% Nt+80% Bt [Nt₂₀Bt₈₀], 40% Nt+60% Bt [Nt₄₀Bt₆₀] and 100% Nt rice [Nt₁₀₀]) on target and non‐target pests in a 2‐year field trial in southern China. The occurrence of target pests, Sesamia inferens, Chilo suppressalis and Cnaphalocrocis medinalis, decreased with the increased ratio of Bt rice, and the mixture ratios with more than 90% Bt rice (Bt₁₀₀ and Nt₀₅Bt₉₅) significantly increased the pest suppression efficiency, with the lowest occurrences of non‐target planthoppers, Nilaparvata lugens and Sogatella furcifera in Nt₁₀₀ and Nt₀₅Bt₉₅. Furthermore, there were no significant differences in 1000‐grain dry weight and grain dry weight per 100 plants between Bt₁₀₀ and Nt₀₅Bt₉₅. Seed mixture sowing of Bt rice with ≤10% (especially 5%) of its parent line was sufficient to overcome potential compliance issues that exist with the use of block or structured refuge to provide most effective control of both target and non‐target pests without compromising the grain yield. It is also expected that the strategy of seed mixture sowing with transgenic Bt rice and the non‐transgenic parental line would provide rice yield stability while decreasing the insecticide use frequency in rice production.     

Does Bt rice pose risks to non‐target arthropods? Results of a meta‐analysis in China

Transgenic Bt rice expressing the insecticidal proteins derived from Bacillus thuringiensis Berliner (Bt) has been developed since 1989. Their ecological risks towards non‐target organisms have been investigated; however, these studies were conducted individually, yielding uncertainty regarding potential agroecological risks associated with large‐scale deployment of Bt rice lines. Here, we developed a meta‐analysis of the existing literature to synthesize current knowledge of the impacts of Bt rice on functional arthropod guilds, including herbivores, predators, parasitoids and detritivores in laboratory and field studies. Laboratory results indicate Bt rice did not influence survival rate and developmental duration of herbivores, although exposure to Bt rice led to reduced egg laying, which correctly predicted their reduced abundance in Bt rice agroecosystems. Similarly, consuming prey exposed to Bt protein did not influence survival, development or fecundity of predators, indicating constant abundances of predators in Bt rice fields. Compared to control agroecosystems, parasitoid populations decreased slightly in Bt rice cropping systems, while detritivores increased. We draw two inferences. One, laboratory studies of Bt rice showing effects on ecological functional groups are mainly either consistent with or more conservative than results of field studies, and two, Bt rice will pose negligible risks to the non‐target functional guilds in future large‐scale Bt rice agroecosystems in China.     

Comparing the predatory performance of green lacewing on cotton bollworm on conventional and Bt cotton

We compared the survival of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) eggs and larvae on Bt and conventional cotton, in the presence or absence of the generalist predator, green lacewing larvae, Mallada signatus, (Schneider) (Neuroptera: Chrysopidae). In small arenas, green lacewings consumed a similar number of H. armigera eggs (ave. 15.8 ± 1.3 on conventional, 12.6 ± 1.4 on Bt cotton per predator over 24 h) and larvae (ave. 6.8 ± 0.7 conventional, 6.5 ± 0.8 Bt per predator over 24 h) whether on Bt or conventional cotton leaves. Likewise, similar numbers of eggs were consumed by each lacewing larva searching whole plants of either Bt (ave. 15.5 ± 0.6 of 49 over 24 h) or conventional (ave. 13.6 ± 1.1 of 49 over 24 h). On conventional plants over 72 h, survival of H. armigera larvae was 72.8% and decreased to 37.7% when lacewings were present, giving a net consumption rate of 35.1% (8.6 prey per predator over 72 h). On Bt cotton plants, 13.6% of the H. armigera larvae survived after 72 h and this decreased to 1.7% when lacewings were present. This combination of mortality factors operated synergistically. Helicoverpa armigera larvae moved to fruiting structures on conventional or Bt cotton but failed to survive in the squares (young flower buds) when the impacts of Bt and lacewings were combined. The removal of first to second instar H. armigera larvae from squares of Bt cotton by predators has the potential to reduce immediate pest damage and, perhaps more importantly, remove potentially Bt‐resistant genotypes.     

Spider mite infestations reduce Bacillus thuringiensis toxin concentration in corn leaves and predators avoid spider mites that have fed on Bacillus thuringiensis corn

Perceived benefits of insecticidal transgenic crops include reduced usage of broad‐based insecticides, and therefore lower risk to non‐target organisms. Numerous studies have documented low or no direct toxicity of Bacillus thuringiensis (Bt)‐derived toxins against non‐target organisms, but there has been less research on (a) effects of secondary pest infestations on Bt expressing in crops and (b) behavioural responses by predators feeding on host arthropods from Bt crops – both topics are investigated in this study. We quantified predation by the obligate spider mite predator Phytoseiulus persimilis of carmine spider mites (Tetranychus cinnabarinus), reared on Bt or non‐Bt corn (Zea mays). Both no‐choice and two‐choice studies were conducted. In addition, we quantified toxin levels in corn leaves with/without spider mite infestation. Under no‐choice conditions, P. persimilis consumed non‐Bt spider mites at a faster rate than Bt spider mites. Under two‐choice conditions, P. persimilis spent more time in the vicinity of non‐Bt spider mites than near Bt spider mites. Corn infested with spider mites exhibited lower toxin levels than non‐infested plants. These results suggest potentially complex interactions among non‐target herbivores, their natural enemies and Bt crops.     

Effects of food nutritive quality and Bacillus thuringiensis onfeeding behaviour, food utilization and larval growth of spruce budworm Choristoneura fumiferana (Clem.) when exposed as fourth- and sixth-instar larvae

Abstract 1 Feeding behaviours, and lethal and sublethal (growth, development and food utilization) effects of Foray 48B, a commercial formulation of Bacillus thuringiensis (kurstaki), were investigated on fourth‐ and sixth‐instar spruce budworm larvae according to food nutritive quality. Nitrogen and soluble sugar content of artificial diets were modified to obtain three different qualities of food, simulating variations in nutritive quality of host tree. 2 Larval development times were longer for Bt‐treated larvae and pupal weights were reduced for sixth‐instar larvae only. Bt‐induced mortality levels were influenced by food quality. Ingested dose of Bt and feeding inhibition times were strongly affected by the Bt treatment, but food quality affected only fourth‐instar larvae. Except for food digestibility, nutritional indices were negatively affected by the Bt treatment and by the reduction in food quality. 3 Contrary to early treated larvae (fourth instar), larvae treated at the beginning of the sixth instar were not able to compensate for Bt injury and were consequently more affected by the Bt‐treatment both in terms of lethal and sublethal effects. 4 Bt efficacy was not directly related to the ingested dose. 5 Increase in larval vulnerability to Bt was more likely a consequence of a general stress induced by a less suitable food than a direct interaction between Bt and food nitrogen or sugar compounds. 6 The application of Bt on late‐instar larvae could be a successful operational strategy at low population levels when field sprays target the insect instead of foliage protection.     

Analysis of soil dwelling rove beetles (Coleoptera: Staphylinidae) in cultivated maize fields containing the Bt toxins,Cry34/35Ab1 and Cry1F×Cry34/35Ab1

In this study, the potential exposure of non-targeted adult rove beetles and their larvae to Bt toxins (Cry34Ab1, Cry35Ab1, Cry1F (59122 and 1507×59122) designed to target western corn rootworm and European corn borer has been determined. The overall assemblage was not significantly affected by the production of stacked proteins.     

Interaction of acid exudates in chickpea with biological activity of Bacillus thuringiensis towards Helicoverpa armigera

The gram pod borer, Helicoverpa armigera, is one of the most important constraints to chickpea production. High acidity of chickpea exudates is associated with resistance to pod borer, H. armigera; however, acidic exudates in chickpea might influence the biological activity of the bacterium, Bacillus thuringiensis (Bt), applied as a foliar spray or deployed in transgenic plants for controlling H. armigera. Therefore, studies were undertaken to evaluate the biological activity of Bt towards H. armigera on chickpea genotypes with different amounts of organic acids. Significantly lower leaf feeding, larval survival and larval weights were observed on ICC 506EB, followed by C 235, and ICCV 10 across Bt concentrations. Leaf feeding by the larvae and larval survival and weights decreased with an increase in Bt concentration. However, rate of decrease in leaf feeding and larval survival and weights with an increase in Bt concentration was greater on L 550 and ICCV 10 than on the resistant check, ICC 506EB, suggesting that factors in the resistant genotypes, particularly the acid exudates, resulted in lower levels of biological activity of Bt possibly because of antifeedant effects of the acid exudates. Antifeedant effects of acid exudates reduced food consumption and hence might reduce the efficacy of Bt sprays on insect‐resistant chickpea genotypes or Bt‐transgenic chickpeas, although the combined effect of plant resistance based on organic acids, and Bt had a greater effect on survival and development of H. armigera than Bt alone.     

Synergism between Bacillus thuringiensis and Xenorhabdus nematophila against resistant and susceptible Plutella xylostella (Lepidoptera: Plutellidae)

The diamondback moth (DBM) Plutella xylostella (L.) is one of the most destructive pests of crucifer crops in many parts of the world. Inappropriate applications have caused DBM to become resistant to most insecticides. We tested the combined effects of the bacteria Bacillus thuringiensis (Bt) and Xenorhabdus nematophila (Xn) against DBM. Populations of Bt-resistant moths (DBM-R), selected repeatedly with B. thuringiensis subsp. kurstaki HD-73 (Bt HD-73), showed resistance rates of 105.43 and 0.92 for Bt HD-73 and X. nematophila HB310 (Xn HB310), respectively. These results not only indicated that DBM-R is highly resistant to Bt HD-73 and only slightly resistant to Xn HB310, but also showed that there is no interactive resistance between the two bacteria. For the third-instar larvae of DBM-R and DBM-S, no significant differences were found in the oral insecticidal activities of Bt HD-73?+?Xn HB310 combination treatments or Bt HD-73 alone. However, mortality rates were significantly increased in response to Xn HB310?+?Bt HD-73 when compared with the Xn HB310-alone treatment. These results demonstrate a synergism of Bt on Xn, but no such effect of Xn on Bt. Therefore, our findings highlight the potential for both bacteria to be used in a mixture for field applications.     

Reduced Mythimna separata infestation on Bt corn could benefit aphids

Use of genetically engineered plants that express insecticidal Cry proteins derived from Bacillus thuringiensis (Bt) have been proven efficacious for managing lepidopteran pests. However, in some cases herbivores that are not targeted by the Bt trait have increased in importance. It has been suggested that reduced caterpillar damage to Bt crops could lead to decreased levels of induced plant defensive compounds which might benefit other non-target herbivores. Here we investigated the potential effect of reduced damage by larvae of Mythimna separata on aphid populations in Bt corn. We compared the performance of Rhopalosiphum maidis feeding on non-Bt corn plants that had been infested by M. separata larvae or were uninfested. The results showed that caterpillar-infested corn plants significantly reduced the fitness of R. maidis leading to a prolonged nymphal development time, reduced adult longevity and fecundity compared to uninfested plants. Consequently, the population growth rate of corn aphids feeding on caterpillar-infested corn plants was significantly lower than on uninfested plants. As expected, the aphids performed significantly better on Lepidoptera-resistant Bt corn than on non-Bt corn when plants were infested with M. separata, since the caterpillars caused very little damage to the Bt plants. The current findings indicate that reduced M. separata infestation could benefit aphid development in Bt corn. Bt corn has the potential to be commercialized in China in the near future and aphids and other non-target pests should be monitored in the farming fields.